Cam and tappet mechanism

ABSTRACT

A CAM AND TAPPET MECHANISM INCLUDING A CAM AND A ROLLER ROTATABLY MOUNTED UPON A TAPPET, WITH THE TAPPET BEING MOUNTED IN A MANNER TO PERMIT OF ANGULAR MOVEMENT OF THE ROLLER IN A PLANE CONTAINING THE AXIS OF ROTATION OF THE CAM.

Feb.v 1.971'v n l Animals-WAy 37,561,288

' GAM AND TAPPET MEcHANIsM Filed Feb. 4,-1969 j v y 2 Sheets-Sheet 1 vINVEN'I'OI? BY .zz,

ATTORNEYS Feb;9',1971 AQKMISHVRA I 3,561,288

' CAM ANDv TAPPET MECHANISM Filed Feb.A 4. 1969 2 Sheets-Sheet 2 INVENTC" United States Patent O 3,561,288 CAM AND TAPPET MECHALNISM Anil Kumar Mishra, Pittsburgh, Pa., assignor to C.A.V. Limited, London, England Filed Feb. 4, 1969, Ser. No. 796,380 Claims priority, application Great Britain, Feb. 7, 1968,

s Int. cl F1611 53/00 U.S. Cl. 74-569 2 'Claims ABSTRACT F THE DISCLOSURE A cam and tappet mechanism. including a cam and a roller rotatably mounted upon a tappet, with the tappet being mounted in a manner to permit of angular movement of the roller in a plane containing the axis of rotation of the cam.

BACKGROUND OF THE INVENTION This invention relates to cam and tappet mechanism of the -kind comprising a rotary cam, a tappet, a roller rotatably mounted upon the tappet for co-operation with the cam and a plunger part which is guided for movement in a plane substantially at right angles to the axis of rotation of the cam, said part being contacted by the tappet to effect said movement.

With such mechanisms it has been found that after use tracking of the surfaces of the cam and roller has occured indicating that the roller surface has not been bearing properly upon the surface of the cam and the object of this invention is to provide such a mechanism in a form in which the tracking is minimized.

SUMMAIRY OF THE lINVENTION According to the invention in a mechanism of the kind set forth the roller is of annular form and has a cylindrical outer surface and a spherical inner surface, the roller is mounted about an annular part carried by a pin secured to the tappet and the annular part is provided with an outer surface complementary to the internal surface of the roller whereby the axis of rotation of the roller can move relative to the axis of the pin.

Moreover, the roller may be of hollow cylindrical form and an intermediate annular part having its internal and external peripheral surfaces complementary to` those of the roller and the rst mentioned annular part is located between the roller and the rst mentioned annular part.

BRIEF DESCRIPTION OF THEDRAWINGS In the accompanying drawings:

FIG. 1 is a sectional elevation of one example of a mechanism in accordance with the invention,

RIG. 2 is a view similar to FIG. 1 but taken at right angles relative thereto,

FIG. 3 is a sectional side elevation of another example of a mechanism, and

FIG. 4 is a sectional side elevation of a further example.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and 2, a cam 10` is mounted upon a rotary shaft 9 and for co-operation with the periphery of the cam', there is provided a roller 15. The roller is mounted for rotation about a pin 16, the axis of which is ICC contained in a plane which includes the axis of rotation of the shaft.

The pin |16 is mounted 'within a cup shaped tappet 17 having a at surface presented and in use, contacted by a curved end surface of a plunger like part 18 slidable in a body part, a portion of which is shown at 19. The ends of the pin 16 extend beyond the tappet and are slidably accommodated within grooves 20 respectively formed on the internal periphery of an annular part 21. The annular part 21 is mounted in the body part for rocking movement about an axis at right angles to the axis of rotation of the shaft and for this purpose pins 22 are provided. By this arrangement, the surface of the roller 15 can closely follow the surface of the cam. The fact that the end surface of the plunger part 118 is provided with a convex surface facilitates the rocking movement. If desired, the surface of the tappet 17 which is presented to the plunger part may be provided with a convex surface.

In the arrangement shown in FIG. 3, there is provided a cam 10 for co-operation with a roller assembly 11. The roller assembly includes a pin 912 which is secured in a surrounding cup-shaped tappet (not shown). The tappet is guided for movement in a surrounding body part and mounted within the body part is a reciprocable plunger part which is contacted by the tappet.

The roller pin 12 carries an annular part 13- which has a spherical surface. Furthermore, a roller 14 has an internal surface complementary to the surface of the part 13 and is mounted about the annular part. By this arrangement, even though the tappet is guided for movement in the body part, the axis of rotation of the roller 14 can move angularly in a plane containing the axis of r0- tation of the cam and as a result thereof the surfaces of the roller and the cam align themselves irrespective of any slight misalignment of the tappet and cam.

In the arrangement shown in FIG. 4, the roller 14 is of annular form and is provided with a cylindrical internal peripheral surface. In this example, the roller 14 is mounted on the part 13 by way of an intermediate part 14a having external and internal surfaces complementary to those of the roller and the part 13 respectively.

The cam and tappet mechanism described has particular application in liquid fuel pumping apparatus for supplying fuel to internal combustion engines and more particularly to pumps of the so called jerk type. In such pumps the plunger part 18 is loaded by a coiled compression spring againstthe action of the cam. In an arrangement where the tappet is positively guided in the body part and the roller is mounted thereon, after extended use tracking of the surfaces of the roller and the permit the surfaces of the roller and cam to be correctly cam has been observed indicating that these surfaces are not in proper engagement. The above arrangements aligned irrespective of any slight misalignment of the cam or any other part.

Having thus described my invention what l claim as new and desire to secure by Letters Patent is:

-1. A cam and tappet mechanism including a rotary cam, a tappet, a roller rotatably mounted upon the tappet for line contact with the cam, and a plunger part guided for movement in a plane substantially at right angles to the axis of rotation of the cam, the plunger part being contacted by the tappet to effect the movement, said roller being of annular form and having a cylindrical outer surface and a spherical inner surface, a pin secured to the tappet, an annular part carried by the pin and bearing against the pin throughout its length, the roller being omunted about the annular part, and said annular part having an outer surface cornplementary to the internal surface of the roller whereby the axis of rotation of the roller can move relative to the axis of the pin.

2. The cam and tappet mechanism as claimed in claim 1 in which the roller is of hollow cylindrical form and an intermediate annular part having its internal and external peripheral surfaces complementary to those of the roller and the first mentioned annular part is located between the roller and the first mentioned annular part.

References Cited UNITED STATES PATENTS 1,061,700 5/1913 Steinbecker 74-569 1,461,560 7/1923 Rich 74-569 5 2,573,506 10/1951 Stokes 74-569 2,735,313 2/1956 Dickson 74-569 2,877,662 3/1959 Woydt 74-569 FRED C. MATTERN, I R., Primary Examiner F. D. SHOEMAKER, Assistant Examiner U.S. Cl. X.R. 

